Methods, systems, and devices for closing a patent foramen ovale using mechanical structures

ABSTRACT

A medical device is disclosed that can include a first atrial anchor, a first delivery shaft linked to the first atrial anchor, wherein the first delivery shaft is adapted to move the first atrial anchor, a second atrial anchor, a second delivery shaft linked to the second atrial anchor, wherein the second delivery shaft is adapted to move the second atrial anchor, and a biasing member linking either (i) the first atrial anchor to the first delivery shaft or (ii) the second atrial anchor to the second delivery shaft. The medical device can include an insulation material coupled to one or more of the first or second atrial anchors, or the first or second delivery shaft. A method for treating an internal tissue opening is also disclosed wherein a first and second electrode can be operated between unipolar and bipolar modes to initiate tissue damage, thereby inducing tissue regrowth.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 11/754,936,filed May 29, 2007, and entitled METHODS, SYSTEMS, AND DEVICES FORCLOSING A PATENT FORAMEN OVALE USING MECHANICAL STRUCTURES, pending,which claims the priority of provisional application Ser. No.60/803,479, filed on May 30, 2006, and provisional application Ser. No.60/809,566, filed on May 31, 2006, the disclosures of each of which arealso incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates generally to medical devices and methodsof use for closing tissue openings. More particularly, the presentinvention relates to devices, systems, and methods for closing a patentforamen ovale (“PFO”).

2. The Relevant Technology

Physical malformations or defects that are present at birth can bedetrimental and even lethal when left uncorrected. A PFO is an exampleof a cardiac birth defect that can be problematic and even result indeath when combined with other factors such as blood clots or othercongenital heart defects. A PFO occurs when an opening between the uppertwo chambers of the heart fail to close during or after birth. Thisbirth defect is sometimes also known as a “hole in the heart.”

Some of the problems associated with a PFO can occur when a blood clottravels between the left and right atria of the heart through the PFO,and ends up on the arterial side. A blood clot in the left atrium can bepassed through the aorta and travel to the brain or other organs, andcause embolization, stroke, or a heart attack. A PFO can be treated bybeing closed by a surgical procedure. Additionally, other similardefects (e.g., septal or otherwise) where some tissue needs to be closedin order to function properly can include the general categories ofatrial-septal defects (“ASDs”), ventricular-septal defects (“VSCs”) andpatent ductus arterosus (“PDA”), and the like.

FIGS. 1A-1C depict various views of a heart having a PFO. The heart 10is shown in a cross-section view in FIG. 1A. In a normal heart 10, theright atrium 30 receives systemic venous blood from the superior venacava 15 and the inferior vena cava 25, and then delivers the blood viathe tricuspid valve 35 to the right ventricle 60. However, in thedepicted heart 10 a septal defect, which is shown as a PFO 50, ispresent between right atrium 30 and left atrium 40.

The PFO 50 is depicted as an open flap on the septum between the heart'sright atrium 30 and left atrium 40. In a normal heart 10, the leftatrium 40 receives oxygenated blood from the lungs 40 via pulmonaryartery 75, and then delivers the blood to the left ventricle 80 via thebicuspid valve 45. In a heart 10 having a PFO 50 some systemic venousblood also passes from the right atrium 30 through the PFO 50 and mixeswith the oxygenated blood in left atrium 40, and then is routed to thebody from left ventricle 80 via aorta 85.

During fetal development of the heart 10, the interventricular septum 70divides the right ventricle 60 and left ventricle 80. In contrast, theatrium is only partially partitioned into right and left chambers duringnormal fetal development, which results in a foramen ovale fluidlycoupling the right and left atrial chambers. As shown in FIG. 1B, whenthe septum primum 52 incompletely fuses with the septum secundum 54 ofthe atrial wall, the result can be a tunnel 58 depicted as a PFO 50, oran ASD (not shown).

FIG. 1C provides a view of the crescent-shaped, overhangingconfiguration of the septum secundum 54 from within the right atrium 30in a heart 10 having a PFO 50. The septum secundum 54 is defined by itsinferior aspect 55, corresponding with the solid line in FIG. 1C, andits superior aspect 53 represented by the phantom line, which is itsattachment location to the septum primum 52. The septum secundum 54 andseptum primum 52 blend together at the ends of the septum secundum 54.The anterior end 56 a and posterior end 56 p are referred to herein as“merger points” for the septum secundum 54 and septum primum 52. Thelength of the overhang of the septum secundum 54, which is the distancebetween superior aspect 53 and inferior aspect 55, increases towards thecenter portion of the septum secundum as shown.

The tunnel 58 between the right atrium 30 and left atrium 40 is definedby portions of the septum primum 52 and septum secundum 54 between themerger points 56 a and 56 p which have failed to fuse. The tunnel 58 isoften at the apex of the septum secundum 54 as shown. When viewed withinright atrium 30, the portion of the septum secundum 54 to the left oftunnel 58, which is referred to herein as the posterior portion 57 p ofthe septum secundum, is longer than the portion of the septum secundum54 to the right of tunnel 58, which is referred to herein as theanterior portion 57 a of the septum secundum. In addition to beingtypically longer, the posterior portion 57 a also typically has a moregradual taper than the anterior portion 57 a as shown. The anteriorpocket 59 a is the area defined by the overhang of the anterior portion57 a of the septum secundum 54 and the septum primum 52, and it extendsfrom the anterior merger point 56 a toward the tunnel 58. Similarly, theposterior pocket 59 p is the area defined by the overhang of theposterior portion 57 p of septum secundum 54 and the septum primum 52,and it extends from the posterior merger point 56 p toward the tunnel58.

Conventional treatments for PFO, and other related conditions havegenerally involved invasive surgery, which also presents risks to apatient. Although there are some less invasive treatments for PFO, suchtreatments have been less efficient at closing the PFO opening thantechniques involving invasive surgery.

BRIEF SUMMARY OF THE INVENTION

The invention relates to a medical device, system and method of use forreducing the size of an internal tissue opening, such as a PatentForamen Ovale (“PFO”). In one embodiment, the medical device can includea biasing member, such as a spring. The biasing member can link twospaced apart atrial anchor or can link an atrial anchor or electrode toa delivery shaft for use in positioning the atrial anchor in a heart.The biasing member may alternatively be linked to the right atrialanchor and associated delivery shaft, or may be linked to the leftatrial anchor and the left atrial anchor delivery shaft. In this manner,the biasing member can facilitate regulation of the amount of forceapplied to the PFO during placement of the medical device. In analternative embodiment, the medical device can include multiple biasingmembers. For example, in one embodiment, a first spring links the rightatrial anchor to a right atrial anchor delivery shaft, and a secondspring links the left atrial anchor to a left atrial anchor deliveryshaft.

In an alternative embodiment of the invention, the medical device caninclude insulating layers thereby enabling energy, such as radiofrequency (“RF”) energy, to be applied to desired tissue areas fortreatment of a PFO. For example, insulating layers can be applied to theleft atrial anchor, right atrial anchor, a shaft portion which may bepositioned in the tunnel of the PFO when the medical device ispositioned to treat the PFO, or any combination thereof. The left atrialanchor, right atrial anchor and/or shaft can be conductive to RF energyor can otherwise aid with delivering RF energy to the area of treatment.The insulating layers can be sized and configured so as to enablevarious amounts of RF energy to pass to adjacently positioned tissue.For example, if a lesser amount of RF energy is to be applied to adesired tissue area, an insulating layer can be used. More insulationcan reduce the conductivity of the insulated portion of the medicaldevice.

The invention also relates to a system for treating a PFO by alternatingright and left atrial anchors between unipolar and bi-polar modes.Furthermore, the time duration of each application of RF energy can bevaried according to determined treatment plans. For example, RF energycan be applied to the PFO by alternating the right and left atrialanchors between unipolar and bi-polar modes, for differing durations.Furthermore, the application of RF energy can be random or repetitive.

In accordance with one embodiment of the invention, the medical devicecan include first and second atrial anchors each having one or morecompliant arms. The compliant arms can be sized and configured todeflect during engagement with tissue surrounding the PFO. In analternative embodiment, the medical device can include a first atrialanchor, a delivery shaft linked to the first atrial anchor, and one ormore hinges linking the first atrial anchor to the delivery shaft,wherein the first atrial anchor can move relative to the delivery shaft.

In an alternative embodiment, the medical device can include a firstelectrode coupled to the right atrial anchor, and a second electrodecoupled to the left atrial anchor. In another embodiment of theinvention, the medical device can include a left atrial anchor, a rightatrial anchor, and a first and second electrode coupled to either theright or left atrial anchor. In yet another embodiment of the invention,the medical device can also include a right and left atrial anchor whichare electrically common elements.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1A-1C illustrates exemplary view of a heart having a Patent ForamenOvale;

FIGS. 2A-2D illustrate a schematic representation of one embodiment ofthe medical device according to the present invention;

FIG. 3 illustrates a schematic representation of one embodiment of aleft atrial anchor of the medial device of the present invention;

FIG. 4 illustrates a graphical representation of operating electrodes totreat an internal tissue opening;

FIG. 5 illustrates a schematic representation of one embodiment of acompliant right atrial anchor of the medial device of the presentinvention;

FIG. 6 illustrates a schematic representation of one embodiment of acompliant left atrial anchor of the medial device of the presentinvention;

FIGS. 7A-7E illustrate schematic representations of embodiments of amedical device, including a biasing member, of the present invention;

FIGS. 8A-8C illustrate schematic representations of embodiments of amedical device of the present invention;

FIGS. 9A-D illustrate schematic representations of embodiments of amedial device of the present invention;

FIGS. 10A-10B illustrate schematic representations of embodiments oflobed atrial anchors of a medical device of the present invention;

FIGS. 11A-11B illustrate a schematic representation of balloon-typemedial devices of the present invention;

FIG. 12 illustrates a schematic representation of another embodiment ofa medial device of the present invention;

FIGS. 13A-B illustrate a schematic representation of one embodiment of amedial device of the present invention;

FIGS. 14A-F illustrate schematic representations of embodiments of amedial device of the present invention;

FIGS. 15A-C illustrate a schematic representation of one embodiment of amedial device of the present invention;

FIG. 16 illustrates a schematic representation of one embodiment of amedial device of the present invention;

FIG. 17 illustrates a schematic representation of one embodiment of amedial device of the present invention;

FIGS. 18A-18B illustrate a schematic representation of anotherembodiment of a medical device of the present invention;

FIG. 19 illustrates a schematic representation of one embodiment of amedial device of the present invention; and

FIGS. 20A-C illustrate schematic representations of embodiments of amedical device of the present invention.

DETAILED DESCRIPTION

The present invention extends to systems, methods, and apparatus forreducing the size of an internal tissue opening. By way of explanation,the devices disclosed herein can be used for a variety of internaltissue opening, although, for purposes of simplicity, frequent referenceis made herein to reducing the size of or closing an opening in hearttissue known as Patent Foramen Ovale (“PFO”). Accordingly, it will beunderstood that references to PFO openings are not limiting of theinvention.

In the following description, numerous specific details are set forth toassist in providing an understanding of the present invention. In otherinstances, aspects of PFO closure devices or medical devices in generalhave not been described in particular detail in order to avoidunnecessarily obscuring the present invention. In addition, it isunderstood that the drawings are diagrammatic and schematicrepresentations of certain embodiments of the invention, and are notlimiting of the present invention, nor are they necessarily drawn toscale.

Illustrative embodiments of the invention relate to delivering radiofrequency or RF energy to tissue adjacent or near to a PFO, such as theseptal wall of the heart, to treat the PFO. In order to treat this typeof defect it can be desirable to have an electrode system that canposition the walls of the flap-like defect toward each other or togetherwhile energy is applied to the wall tissue to “weld” the defect closed,i.e. damage the tissue to stimulate tissue growth in the area.Furthermore, it can be desirable to have a system that can enable apractitioner to more effectively determine the morphology of the PFO,the amount of RF energy to apply, as well as the amount of time to applysuch amount of RF energy.

In one embodiment, the medical device can include an electrodeconfigured to increase the effectiveness of the tissue weld. Theeffectiveness of the tissue weld can be increased by configuring theelectrode to contact, and in some instances conform with, the tissue ofthe atrium proximate the opening of the PFO. Furthermore, the electrodecan be configured to be collapsible to a small cross section to removethe electrode from the welded tissue opening without substantiallyinterfering with the damaged tissue. While the term electrode is usedfrequently herein, it will be appreciated that the word anchor can alsobe used interchangeably with electrode when the electrode also functionsto physically pinch or close the PFO, or otherwise physically reduce thesize of the PFO. Furthermore, an anchor can also serve as an electrodeas needed or can be non-conductive to RF energy or other type of energyusable to “tissue weld” the PFO closed, thus acting as an insulator.Alternatively, the anchor can be partially conductive to RF energy andpartially insulated.

The present invention generally includes a medical device, withassociated systems and methods, which can be positioned in closeproximity to a PFO, used to position the septum secundum and/or septumprimum to close the PFO, and then close the PFO using one or morevarious techniques or methods. The medical device can be positionedeither directly or through the use of other medical devices, such as,but not limited to, one or more actuators, catheters, introducer tubes,guidewire, or other medical device(s) that can be used to positionand/or actuate the medical device.

The following discussion will be directed to various configurations ofthe medical devices, systems, and methods according to the presentinvention, but it will be understood that the described medical devices,systems and methods are only illustrative embodiments and do not limitthe applicability of the general disclosure of the invention to otherconfigurations and embodiments of medical devices, systems and methodsthat are capable of closing an opening within the heart or other bodylumen of a patient. Further, although not illustrated, it will beunderstood that any of the described medical devices, systems, andmethods can include an integral soft tip, such as an atraumatic tip,J-hook, etc. to aid with guiding the medical device. In addition, any ofthe described medical devices, systems, and methods can cooperate with aseparate guidewire that aids with navigating and positioning the medicaldevice into the appropriate location, if desirable.

It will be understood by one of ordinary skill in the art in view of thedisclosure provided herein that when RF energy is discussed below as aclosure means, other methods or means of heating tissue to close a PFOmay be utilized, such as optical, laser, acoustic, ultrasonic, hotfluid, resistive, microwave, or other means of heating the tissues.Furthermore, while reference is made specifically to PFO'S, it will beunderstood that the systems, methods and apparatus of the presentinvention may be used to reduce the size or close other tissue openings,such as an Atrial Septal Defect (ASD) or other openings in cardiac orother tissues. “Closing” can also refer to joining of tissues, i.e. notnecessarily closing an opening, but simply joining tissue to othertissue. Examples include tubal ligation, vascular ligation, wound ordefect closure, and others. Also the terms for “electrodes”, “anchors”,or “clamps” can be generally used interchangeably.

In tissue welding by thermal means, it can be desirable to control thedistribution of energy, and thus, heating of the tissue being treated.In the application of RF energy, the energy delivered to the tissuesfollows an infinite number of parallel paths from one electrode toanother or to a ground. The electrical energy will concentrate itself inshorter or lower impedance paths. The following discussion relates tovarious configurations of medical devices and the energy flowcharacteristics thereof. The descriptions are primarily for two bipolarelectrodes where the current flow is between the two electrodes.However, the principles also hold for unipolar electrodes in which thecurrent flow is between the electrode and a return electrode or ground,which return electrode or ground can be generally placed on the skin ofa patient, such as on the patient's leg.

It can be desirable to heat the tissue of the inner surface of the PFOtunnel. However, efficient heating may be obtained when the surroundingtissues are also heated so as to reduce heat migration away from theimmediate vicinity of the PFO tunnel to the surrounding tissues. Suchheat transfer can reduce the effectiveness of the heat treatment due tocertain areas of the tunnel not achieving a desired temperature.Additionally, it can be desirable to heat the tissues surrounding thePFO to create a more generalized response beyond the PFO tunnel. As anexample, if tissues surrounding a PFO are damaged, thus promoting ahealing response, this may serve to encourage and facilitate the healingresponse inside the PFO tunnel itself, thus increasing the likelihood ofsuccessful PFO closure.

Note also that at RF frequencies, electrical energy may be coupled fromelectrodes to tissues via either conductive or capacitive means, i.e.even insulated electrodes can be used to heat tissue. The energytransfer characteristics may be modified (but not necessarilyeliminated) by insulation thickness, location, or by its presence orabsence. In this manner, heating may be accomplished by strategicallyplacing insulation in prescribed amounts along the length of, or on thesurfaces of, an electrode to achieve desirable heating patterns.

FIGS. 2A and 2B illustrate an exemplary, basic structure of a closuredevice 100; FIG. 2A illustrates the closure device 100 prior todeployment, while FIG. 2B illustrates the closure device 100 in positionfor application of radio frequency (RF) energy to close the tissueopening, such as the PFO. In the illustrated embodiment, closure device100 can include a left electrode 114, with associated delivery shaft110, a right electrode 111, with associated right electrode catheter104, and a delivery sheath 102 configured to facilitate positioning ofleft and right electrodes 114, 111. A soft atraumatic tip 120 can becoupled to a distal end of left electrode 114 to facilitate placement ofclosure device 100 and to aid with passage of the closure device 100through the tortuous anatomy of a patient. Optional insulation 108 canbe provided on adjacent surfaces of delivery shaft 110 and/or rightelectrode catheter 104 to electrically isolate delivery shaft 110, andso the left electrode 114, from right electrode catheter 104, and so theright electrode 111.

In the illustrated embodiment, left electrode 114 can include one ormore arms 116 coupled to or formed with a delivery shaft 110. Anactuating shaft 118 is coupled to a distal end of left electrode 114 tofacilitate deployment of one or more arms 116 after one or more arms116, and optionally a portion of the delivery shaft 110, have beendeployed from a right electrode catheter 104. The actuating shaft 118can be moved proximally to allow the arms 116 to flex and form the leftelectrode 114 illustrated in FIG. 2B. Moving the actuating shaft 118distally returns the arms 116 to the configuration illustrated in FIG.2A. Actuating shaft 118 can be received and at least partially housed indelivery shaft 110, such that actuating shaft 118 is capable ofmovement, both rotational and translational, with respect to deliveryshaft 110.

With continued reference to FIGS. 2A-2B, left electrode delivery shaft110 can be received, and translated and/or rotated, within rightelectrode catheter 104. This again can aid with positioning the closuredevice 100 within the left atrium of the heart. As shown in theillustrated embodiment, the left electrode 114 can be inserted throughthe opening of the PFO 50. With transcatheter treatment of a PFO throughthe femoral vein and the inferior vena cava into the right and leftatrium of the heart, it is advantageous for the closure device 100,including the delivery sheath 102, the right electrode catheter 104, andthe left electrode 114, with the delivery shaft 110, to have a lowcrossing profile. It is further advantageous for the left electrode 114,including the delivery shaft 110, to have a low crossing profile to aidwith passage through the PFO 50 into the left atrium. A low crossingprofile enables the left electrode 114 of the closure device 100 to bewithdraw through the small opening after the energy delivery and/or“tissue welding” have been accomplished.

Also associated with the closure device 100 is right electrode 111. Asillustrated, right electrode 111 can include one or more arms 112movably coupled to a right electrode catheter 104. These one or morearms 112 can be biased to open outwardly upon being deployed from withindelivery sheath 102 and can be pivotally or hingedly attached or coupledto the right electrode catheter 104. Right electrode catheter 104 canreceive left electrode 114 and delivery shaft 110 therein such that leftelectrode 114 and the delivery shaft 110 can translate and/or rotate inright electrode catheter 104.

For simplicity of discussion, only two arms 116 of left electrode 114and two arms 112 of right electrode 111 are illustrated. However, itwill be appreciated by one of ordinary skill in the art in view of thedisclosure provided herein that left and right electrode 114 and 111 caninclude more than two arms 116 and 112. Additional information regardingleft and right electrodes 114, 111 is disclosed with regards to FIGS. 3and 10A, as well as in U.S. patent application Ser. No. 11/671,428,filed Feb. 5, 2007 (Attorney Docket Number 16348.13.1), the disclosureof which is hereby incorporated by reference in its entirety.

With continued reference to FIGS. 2A and 2B, delivery sheath 102 can beconcentric with and substantially house right electrode catheter 104.When right electrode catheter 104 is extended from delivery sheath 102,right electrode 111 can be deployed so that arms 112 can extend toengage tissue adjacent or near the PFO 50 to facilitate physicallyclosing the PFO 50 in connection with left electrode 114. When rightelectrode catheter 104 is withdrawn into delivery sheath 102, arms 112can collapse and enter the right electrode catheter 104.

Delivery shaft 110 and left electrode 114, when not deployed, can beconcentric with and substantially housed by right electrode catheter104. As mentioned above, delivery shaft 110 can include insulation 108on its exterior surface to provide electric insulation between rightelectrode catheter 104, right electrode 111, and conductive deliveryshaft 110. Alternatively, insulation can be positioned on the interiorsurface of right electrode catheter 104. Furthermore, insulation can bepositioned on both the interior surface of right electrode catheter 104and the exterior surface of delivery shaft 110, or any combinationthereof. Furthermore, as discussed more fully hereinafter, insulationcan be strategically placed on left and/or right electrodes to focus RFenergy as desired.

In the illustrated configuration, left electrode 114 and delivery shaft110 form a continuous piece. However, it will be appreciated that leftelectrode 114 and delivery shaft 110 can form separate and distinctpieces being coupled together to perform the functions set forth herein.Movement of actuating shaft 118 relative to delivery shaft 110 can aidwith deploying the left electrode 114. For instance, delivery shaft 110,with the coupled or formed left electrode 114, can be advanced into theleft atrium 40 (FIG. 1A) and actuating shaft 118 moved proximally todeploy the arms 116, as illustrated in FIG. 2B. Once arms 116 areextended outwardly, delivery sheath 102 can be moved proximally todeploy right electrode 111. In this configuration, actuator shaft 118,with or without delivery shaft 110, can be moved to position the septumsecundum 54 and septum primum 52 for tissue welding or closure of thePFO.

In an alternate configuration, the combination of right electrodecatheter 104, delivery shaft 110, left electrode 114, and actuator shaft118 can be advanced from within delivery sheath 102 to deploy andposition the right electrode 111. With the right electrode 111 deployed,delivery shaft, with associated left electrode 114 and actuator shaft118, can be advanced through the PFO 50. Again, with delivery shaft 110,and the coupled or formed left electrode 114, advanced into the leftatrium 40 (FIG. 2A), actuating shaft 118 can be moved proximally todeploy the arms 116, as illustrated in FIG. 2B.

With the expandable configuration of the left electrode 114, a largesurface area is provided through which RF energy can be passed. Forinstance, left electrode 114 can have an increased surface area outsideright electrode catheter 104 than would otherwise be possible to insertin a patient. In other words, left electrode 114 of the presentinvention can be pushed out of and pulled back into a relatively smalldiameter right electrode catheter 104 and yet expand and have enoughstrength to hold the atrial walls together during energy delivery andsubstantially resist pulling through the PFO. Additional disclosureregarding left electrode will be discussed with regards to FIG. 3, andis disclosed in U.S. patent application Ser. No. 11/671,428, filed Feb.5, 2007.

It will be understood in view of the disclosure provided herein thatinsulation 108 can be sized, configured and positioned such that some orall of the portions of the delivery shaft 110 that are in the PFO tunnelcan delivery RF energy to the tissue in the PFO tunnel. In this manner,delivery shaft 110 can serve as an electrode, either independent from orin connection with left electrode 114, to facilitate delivery of RFenergy to the PFO tunnel.

With arms 112 of right electrode 111 and arms 116 of left electrode 114being positioned in this manner as illustrated, RF energy can be appliedto the tissue which is between arms 112 and arms 116. The application ofenergy in this manner can cause tissue damage. Causing tissue damage inthis manner can initiate tissue regrowth so as to weld the tissuetogether. After such treatment, actuating shaft 118 can be moveddistally to move the one or more arms 116 radially inwardly inpreparation for the delivery shaft 110, with associated left electrode114, to be retracted back through the small remaining hole in the PFO.Thereafter, delivery shaft 110 can be withdrawn without substantiallydisturbing the weak “tissue weld” that has been created by theprocedure.

FIGS. 2C-2D illustrate general representations of a medical deviceoperating in unipolar (FIG. 2C) and bipolar (FIG. 2D) modes. Forexample, FIG. 2C represents an electrode system 138 operating inunipolar mode, the system 138 including at least one electrode 122, suchas a left electrode, right electrode, or other element which can serveas an electrode, in electronic communication with an RF generator 142 cvia an electronic coupling element 126, such as a wire or electroniccable. In unipolar mode, the system 138 includes a return electrode orground 124. Ground 124 can be positioned on the patient's skin, oralternatively, can be a pad on which a patient rests. It will beunderstood that electrode 122 can include multiple electrodes which areelectrically common elements, such that RF energy can be transferredfrom the electrodes 122 to the ground 124. The ground 124 can beelectrically coupled to RF generator 142 c by an electronic couplingelement 128, such as a wire or electronic cable.

In bipolar mode, as illustrated in FIG. 2D, electrode system 140 caninclude a first electrode 130 electrically coupled to an RF generator142 d by an electronic coupling element 134, such as a wire orelectronic cable, and a second electrode 132 electrically coupled to theRF generator 142 d by an electronic coupling element 136, such as a wireor electronic cable. In this manner, RF energy can be passed betweenfirst and second electrodes 130, 132, rather than from the electrodes toa ground, as in the bipolar mode or configuration. It will be understoodin view of the disclosure provided herein that first electrode 130,second electrode 132 and/or electrode 122 can include one or moreelectrically common electrodes.

Generally, medical grade metals, metal alloys, plastics, polymers,synthetics can be used to fabricate the closure device 100 andassociated sheaths, electrodes, catheters, and tips. For instance,delivery shaft 110 and associated left electrode 114 can be fabricatedfrom a shape memory material or superelastic material so that it can beformed to be biased in a tubular configuration, with the actuating shaft118 being movable to overcome the biased configuration and deploy theone or more arms 116 to form the left electrode 114. Such shape memorymaterials can include, but not limited to NiTiNol. Other non-shapememory materials can also be used, such as but not limited to, stainlesssteel, steel, or other metals or metal alloys.

Delivery sheath 102 and right electrode catheter 104 can be fabricatedfrom plastics, polymers, or synthetic materials having the desiredflexibility characteristics. For instance, the materials used caninclude, but not limited to, Pebax, Polyimide, PTFE, Polyolefins,stainless steel braids, copper braids, molybedenum and thermocouplealloy conductors.

Right electrode 111 and left electrode 114 can be fabricated fromconductive materials, such as steel, metal, or metal alloys to enable RFenergy to be delivered to or near the PFO. Alternatively, rightelectrode 111 and left electrode 114 can fabricated from non-conductivematerials, but coated with a conductive film or include a conductivemembers, such as a wire, ribbon, or the like to provide the conductivecharacteristics.

Additional disclosure regarding closure devices, their variousstructures and function, methods of use, methods of delivery andassociated apparatus, electrodes, anchors, or related structures whichcan be used in connection with the present invention can be found andmay be described in various co-pending patent applications, includingU.S. patent application Ser. No. 10/964,311, filed Oct. 12, 2004, U.S.patent application Ser. No. 11/102,095, filed Apr. 8, 2005, U.S. patentapplication Ser. No. 11/534,996, filed Sep. 25, 2006, U.S. patentapplication Ser. No. 11/534,953, filed Sep. 25, 2006, U.S. patentapplication Ser. No. 11/671,428, filed Feb. 5, 2007, U.S. ProvisionalPatent Application No. 60/803,482, filed May 30, 2006, U.S. ProvisionalPatent Application No. 60/809,524, filed May 31, 2006, and U.S. patentapplication entitled “METHODS, SYSTEMS, AND DEVICES FOR SENSING,MEASURING, AND CONTROLLING CLOSURE OF A PATENT FORAMEN OVALE” (AttorneyDocket No. 16348.23.1.1), filed May 29, 2007, the discloses of which arehereby incorporated by reference in their entirety.

The temperature profile in the tissue surrounding the PFO during RFheating can be affected by the geometry of the electrodes 111 and 114.Electrodes 111 and 114 may be operated in either unipolar or bipolarmode. In a unipolar system, the current flows from the active electrodenear the tissue to be heated to a return electrode, for example, on thepatient's skin (not shown). Either or both of the electrodes 111 and 114can be operated in unipolar mode. In bipolar RF heating, the currentflows between two active electrodes in the area to be heated. UnipolarRF heating results in non-uniform heating that is highest next to theelectrode because the current density rapidly decreases as the currentspreads out in the body as it travels toward the return electrode.Bipolar heating can provide a more uniform current density and heatingbecause the current path is from one electrode to the other. In abipolar system, higher current densities and resulting higher heatingrates can occur in areas where the distance between bipolar electrodesis smaller.

Heating using RF energy can be preferentially focused on a desiredlocation, such as in the tunnel area of the PFO. Focused heating can beaccomplished by utilizing bipolar electrodes having higher conductordensity in locations that correspond with focused tissue areas. FIG. 3illustrates an exemplary embodiment of an anchor or electrode 200 whichcan be utilized in connection with preferential heating. In oneembodiment, electrode 200 can be left electrode 114, as described withrespect to FIG. 2. Details regarding electrode 200 can be found and aredisclosed in pending U.S. patent application Ser. No. 11/671,428, filedFeb. 5, 2007, which has been incorporated herein by reference. Forexample, electrode 200 can be configured to have a pattern of radialspokes or arms 202. As the distance between spokes 202 increases towardthe perimeter 204 of the electrode, the conductor density decreaseswhich decreases current density and heating. Heating may be furtheraccentuated in the tunnel area of the PFO by utilizing a conductiveshaft 206 configured to traverse the tunnel area of the PFO, wherein theshaft 206 is one of the heating signal poles in a bipolar electrodesystem.

More uniform heating may be achieved by insulating at least a portion ofshaft 206 and by selectively insulating parts of the right and/or leftelectrodes, such as electrodes 111 and 114, in order to achieve a moreuniform conductor density. Portions of delivery sheath 102, rightelectrode catheter 104, and/or delivery shaft 110, may be insulated bypolymeric coatings such as epoxy, acrylic, silicone, urethane, andparylene. Conductive portions of the electrodes 111 and 114 that are notdesigned to contact the atrial wall may be insulated to preventunintended heating of other cardiac structures and blood. Anotherelectrode arrangement that concentrates heating in the tunnel is toinclude a separate electrode that traverses the tunnel and that acts asone pole with both the right and the left atrial anchor/electrodesconnected to another pole. Another topology that results in high tunnelheating concentration is operating the left electrode in unipolar modewhen delivery shaft 110 serves as an electrode and RF energy can bedelivered from delivery shaft 110.

Changing the mode of operation of the left and right electrodes caneffect the heating and treatment of the PFO. For example, operating theleft and right electrodes between unipolar and bi-polar modes, as wellas modifying the duration and/or power level of each application of RFenergy, can effect the treatment of the PFO. More than one mode ofoperation may be used within one thermal treatment to tailor thetemperature distribution in the tissue surrounding the PFO.

The system of electrodes (i.e., left electrode, right electrode, and anexternal ground electrode) can change modes at a high rate in order toachieve heat distributions that are not possible with a single mode orconnection. For example, FIG. 4 illustrates a portion of an exemplarytreatment having multiple RF energy applications 400, illustrating thechanges in mode, duration and power level of the right and leftelectrodes between RF energy applications 400. In the illustratedembodiment, a first RF energy application 402 can include rightanchor/electrode operating in unipolar mode for a certain duration, suchas few milliseconds, at a certain power level, and then a second RFenergy application 404 can include left anchor/electrode operating inunipolar mode for a duration shorter than the first RF energyapplication 402, but at a higher power level than the first RF energyapplication. In a third RF energy application 406, right and leftelectrodes can be operated in bipolar mode for a duration and at a powerlevel less than either of the first and second RF energy applications402, 404. In a fourth RF energy application 408, right anchor/electrodecan operate in unipolar mode and in a fifth RF energy application 410,right anchor/electrode can operate in unipolar mode again at a higherpower level and longer duration than in the fourth RF energy application408, for example.

It will be appreciated by one of ordinary skill in the art in view ofthe disclosure provided herein that a variety of sequences can beutilized without departing from the scope and spirit of the invention.For example, the modes, patterns, duration and power levels can bemodified. Furthermore, sequences can be repeated for the duration of atreatment or the sequence may be altered during the treatment so thatthe unipolar mode parts of the sequence are favored at the start of theheating cycle and the bipolar mode parts of the sequence are favoredtoward the end of the cycle. Many different sequences of modes andconnections are possible, each with unique spatial and temporal heatdistribution patterns.

The heat profile in the tissue can also be a function of the degree ofelectrical contact between the electrode and the tissue.Anchor/electrodes that are relatively rigid may make contact with thetissue only at high points such as the inferior aspect of the septumsecundum. This may cause locally high current densities and heating.More conformal electrodes will give more uniform current densities andheating. It can be desirable to include separate electrodes coupled tothe anchors. Separate electrodes could be very soft and conformablesince they do not also need to support the device.

It can be desirable for a PFO closure device to mechanically, as well asthermally, accommodate the variety of PFO morphologies. It is anoptional objective of the device of this invention to minimally distortthe anatomy of the PFO while clamping it closed during tissue welding,or in other words, during application of RF energy. In order toaccommodate PFOs with varying tunnel lengths and septal thicknesses, thedistance between the right and left anchor/electrodes may be variable.

One method of setting this distance is to visualize the device in thePFO via fluoroscopic and/or ultrasonic imaging and set this distancemanually. Due to the limitations of these imaging systems, it can bedesirable to have a device which automatically sets the anchor/electrodespacing. This can be accomplished by a mechanism that urges theanchor/electrodes toward each other with a predetermined force that isrelatively constant over a desired range. With the proper amount offorce, the anchor/electrodes can move toward each other until theirmovement is limited by the atrial tissue that is lightly clamped betweenthem. There are several methods of accomplishing this function, whichcan be used independently or in combination with other devices.

The configuration of FIGS. 2A and 2B can urge the electrodes 111 and 114toward each other with a desired and optionally pre-determined forcethat is relatively constant over the desired range. With the properamount of force, the electrodes 111 and 114 can move toward each otheruntil their movement is limited by the atrial tissue that is clampedbetween them. For instance, movement of delivery shaft 110 relative toright electrode catheter 104 can apply force to move the septum secundum54 and septum primum 52 toward each other. Alternatively, and/or incombination with the above, movement of actuating shaft 118 with respectto right electrode catheter 104 can move left electrode 114 to providethe desired force.

In another configuration, maintaining relatively constant force betweenthe anchor/electrodes can be achieved through constructing theelectrodes such that they have axial compliance in their structure.Either the right anchor/electrode or the left anchor/electrode or bothmay have this characteristic to accomplish this goal. For example, FIG.5 illustrates one embodiment of a right anchor 500 having one or morecompliant arms 502 linked to a delivery shaft 504. Compliant arms 502can be sized and configured to provide axial compliance as arms 502contact and engage tissue. Furthermore, arms 502 can be linked to shaft504 in a manner that enables each arm 502 to move independently fromanother arm 502, thus enabling right anchor 500 to better conform to thetissue adjacent the PFO. It will be understood that delivery shaft 110can extend through a portion of the right anchor 500 as discussedpreviously.

FIG. 6 illustrates one embodiment of a left anchor/electrode 614 havingone or more compliant arms 616. In the illustrated embodiment, insteadof being coupled to or formed with the delivery shaft 610, the leftanchor/electrode 614 can be slidably received within delivery shaft 610having a generally uniform cross-section along its length. Leftelectrode 614 of the present invention can be pushed out of and pulledback into delivery shaft 610 with a diameter of about 1 mm, for example,and yet expand to a diameter of about 20 mm, for example, and haveenough strength to hold the atrial walls together during energy deliveryand strongly resist pulling through the PFO. It will be understood, thatthe configuration of FIGS. 2A-2B can incorporate left anchor/electrode614, and can include another delivery tube or shaft within whichdelivery shaft 610 can be received and from which it can be deployed.

With continued reference to FIG. 6, the left anchor/electrode 614 can bedeployed from within delivery shaft 610 through distal movement of arms616, proximal movement of delivery shaft 610, or a combination ofmovement of both of arms 616 and/or delivery shaft 610. The arms 616 arebiased to the illustrated configuration. The arms 616 can be fabricatedfrom NiTiNol, other shape memory or superelastic material, or othersufficiently flexible material, such as stainless steel or plastic, toenable the arms 616 to move to the configuration illustrated in FIG. 6upon deployment of the arms 616. As illustrated, the plurality of arms616 can be slidably received within the delivery shaft 610. A distal end618 is movable out of a distal end of the delivery shaft 610, while theproximal end (not shown) can be slidably received within the deliveryshaft 610 or coupled to delivery shaft 610, such that movement ofdelivery shaft 610 causes movement of arms 616. Arms 616 can be sizedand configured to provide axial compliance as left anchor 614 is pulledback from the left atrium and arms 616 contact and engage the tissueadjacent the PFO. Additional disclosure regarding compliant electrodes,including structural disclosure and methods of use and delivery, can befound in co-pending U.S. patent application Ser. No. 11/534,953, filedSep. 25, 2006, which has been incorporated by reference herein.

Another way to maintain a relatively constant force between theanchors/electrodes is to provide tension or compression spring(s), suchas a spring having a relatively low spring constant for example,adjacent to the anchor/electrodes to urge the anchors/electrodes towardseach other. FIGS. 7A-7E illustrate various embodiments of the inventionwhich incorporate a biasing member, such as one or more springs, toprovide desired compression characteristics.

FIG. 7A illustrates one embodiment of a medical device, such as aclosure device, having a left electrode similar to the left electrode114 disclosed with regards to FIGS. 2A-2B, which can apply desiredcompression forces in a controlled manner to aid with closure of thePFO. FIGS. 7B-7E illustrate general or basic structures of medicaldevices that can also provide desired compression capabilities orcharacteristics. It will be understood that the principles disclosedwith regards to FIGS. 7A-7E can be incorporated into a variety ofdifferent shapes and designs of electrodes disclosed herein and/ordisclosed in the references incorporated herein by reference.

As mentioned herein, it can be desirable to apply a force to close theseptum in a controlled manner to limit the maximum “clamping” or closingforce applied to the septum as a PFO is pulled closed in preparation fora thermal or other treatment to close the PFO. FIG. 7A illustrates oneembodiment of a medical device 700 a having a left electrode 702 alinked to a right electrode 704 a by a compliant section 706 a formedfrom a spring, coil, or other axially compliant element 708 a. Thecompliant section 706 a, such as the axially compliant element 708 a,can be used to limit the peak forces applied to the septum so as to notdamage the septum or distort the PFO independent of the force applied bythe doctor to pull the two electrodes together. The compliant element708 a can be located between left and right electrodes 702 a, 704 a, orat other locations, such as opposite sides of the electrodes. In theillustrated configuration, the left electrode 702 a and right electrode704 a can be mirror images of each other and can be actuated using anactuating shaft 718 a in a similar manner to that described with respectto FIGS. 2A and 2B, i.e., movement of the actuating shaft 718 a ineither the proximal or distal directions to deploy or retract theelectrodes having arms biased to extend outwardly or along thelongitudinal axis of the closure device 700. Additional informationregarding medical device 700 a is disclosed in U.S. patent applicationSer. No. 11/671,428, filed Feb. 5, 2007, which has been incorporated byreference herein.

In FIGS. 7B-7E, basic structures of different closure devices aredisclosed for simplicity. In the illustrated embodiments of FIGS. 7B-7E,the closure device or medical device 700 can include a first anchor 702,a first delivery shaft 704 operatively associated to first anchor 702, asecond anchor 706 movable with respect to first anchor 702, a seconddelivery shaft 708 operatively associated to the second anchor 706, anda biasing member 710. Specific details about first and second anchors,and first and second delivery shafts can be obtained by the disclosureprovided herein and in the incorporated references, with regards toanchors, electrodes, delivery tubes and delivery shafts. It will beunderstood that the anchors can also be considered an electrode, i.e.,RF energy can be passed through the anchor to aid with closing the lumenwithin which the closure device 700 is disposed.

In FIG. 7B, medical device 700 b includes biasing member 710 b extendingfrom second delivery shaft 708 b to second anchor 706 b. In this manner,as medical device 700B is positioned in relation to a PFO, asillustrated in FIGS. 2A-2B, movement of second delivery shaft 708 b inthe proximal direction can enable engagement of second anchor 706 b withthe tissue without applying excess amounts of force to the tissue.Likewise, FIG. 7C illustrates two biasing members 710 c extending tofirst anchor 702 c and second anchor 706 c, respectively. In thismanner, as first delivery shaft 704 c is moved in the distal directionand second delivery shaft 708 c is moved in the proximal direction,biasing members 710 c can absorb some energy thereby reducing the riskof applying excessive pressure to the PFO for closure. FIG. 7Dillustrates biasing member 710 d extending from first delivery shaft 704d to first electrode 702 d.

FIG. 7E illustrates medical device 700 e having a handle 712 e coupledto first delivery shaft 704 e, and biasing member 710 e extending fromfirst delivery shaft 704 e to second delivery shaft 708 e. In thismanner, as second delivery shaft 708 e is moved distally with respect tohandle 712 e, and thus with respect to first delivery shaft 704 e, thedistance between first anchor 702 e and second anchor 706 e increases.Medical device 700 e can be configured such that the distance betweenfirst anchor 702 e and second anchor 706 e is slightly less than the PFOtunnel. In this manner, in order to position second anchor 706 e in theleft atrium when first anchor is positioned adjacent the PFO in theright atrium, a user could compress the biasing member or spring 710 e.Once in place, second anchor 706 e would be forced against the tissue ofthe PFO in the left atrium by biasing member 710 e, thereby providing aclamping or pinching force to reduce the size of the PFO.

As described above, the medical device 700 e of the present inventionincludes handle 712 e configured to enable a user to move the first andsecond anchors/electrodes 702 e and 706 e relative to each other. It canbe understood that one or more handles can be used to move first andsecond electrodes 702 e and 706 e. For example, a first handle can belinked to the first anchor/electrode and a second handle can be linkedto the second anchor/electrode, such that movement of the first handlecauses movement of the first electrode and movement of the second handlecauses movement of the second electrode. An optional travel stop in thehandles can be utilized to limit relative movement between the twohandles to something less than would be required to completely compressor extend the spring element positioned between the twoanchors/electrodes 702 e and 706 e. In that situation, the spring wouldbe selected to exert a desired force or range of forces to the clamp orhold the portions of the PFO or other portion of the body.

As illustrated in FIG. 7E, the biasing member 710 e, such as a spring,or force controlling compliant element can be found in the handle 712 eused by the physician to manipulate the medical device 700 e. In thisembodiment, the biasing member 710 e can be interposed between thehandle the physician manipulates and the catheter connections to theanchors/electrodes 702 e and 706 e inside the patient. An optionaltravel stop (not shown) between the left and right handles cansubstantially prevent the anchors/electrodes 702 e and 706 e frommoving, relative to each other, farther than a desired maximum distance.When the travel limit is reached, the spring element can impose adesired pushing or pulling force on the connections to theanchors/electrodes 702 e and 706 e.

It can also be desirable to not distort the position or shape of theseptum or clamped PFO between the anchors/electrodes 702 e and 706 e byexcessive pulling or pushing. The external handle 712 e and associatedoperating mechanism can be designed to allow the left and rightanchors/electrodes 702 e and 706 e to float axially individually and/oras a pair to allow the septum to rest at its neutral position. This canoccur when the two anchors/electrodes 702 e and 706 e are exerting aclamping force to close the PFO.

It will be appreciated by one of ordinary skill in the art in view ofthe disclosure provided herein that the biasing member can beimplemented on either the right or the left anchor/electrode or on both.In one embodiment, the biasing member, such as a spring, can bepreloaded so that the desired force is achieved when theanchor/electrodes are together. If the biasing members have a relativelylow spring constant, the force urging the anchor/electrodes togetherdoes not change appreciably when they are separated by distances thatcover the range of PFO tunnel lengths and septal thicknesses.

Alternatively, the biasing members, such as one or more low springconstant springs that urge the slidably disposed anchors toward eachother, may be located in the handle unit at their proximal end which isoutside the body. In this embodiment, the springs act on the deliveryshafts, catheters, or tubes that are connected to the anchors orelectrodes. The shafts, catheters, or tubes which are slidably disposedto each other may have PTFE or other low friction sliding surfaces toallow the forces to be transmitted to the anchor/electrodes with minimalfrictional losses.

In addition to anchor/electrode clamping force control, there are anumber of other features of the present invention that can enabletreatment of a PFO while reducing the distortion of the PFO from itsnatural geometry. Other features of the device that provide thisanatomical conformance can include the ability of the right and leftanchor/electrodes to freely pivot and/or flex relative to their deliveryshafts, catheters, or tubes. Flexure can enable the anchor/electrodes tobe positioned against the atrial wall in an optimal manner, which, ingeneral, may not be perpendicular to the axis of the delivery shaft. Anadditional feature can include the ability of the arms of the right andleft anchor/electrodes to move independently and adapt to non-planarsurface topology to seek optimal contact with the atrial wall. Yetanother feature can enable the ability of the delivery shafts of theright and left anchor/electrodes in the area just proximal to the PFO tofreely pivot or flex. This allows the shafts to assume the shaperequired by the pathway from the inferior vena cava and through the PFOwithout substantially altering the orientation of the PFO.

Additionally, adequate flexibility of the delivery shafts can alsoenable the patency of the PFO to be evaluated after treatment but priorto device removal without high risk of tearing open the just-weldedflaps. The patency can be evaluated by any of the methods discussed inthis disclosure with the clamping force removed and theanchor/electrodes moved apart, but with the left anchor/electrode shaft,catheter, or tube remaining in the PFO tunnel. If residual patency isdetected, further treatments can be administered without the difficultyof re-crossing the PFO.

FIGS. 8A-8C illustrate exemplary embodiments of another closure deviceor medical device 800. While the illustrations in FIGS. 8A-8C are verygeneral for simplicity, it is intended that these principles can beapplied to the electrode and/or anchor configurations disclosed hereinor in the disclosures of the references incorporated herein. Generally,medical device 800 can include a right anchor 802, a right anchordelivery shaft 804 coupled to right anchor 802, a left anchor 806 and aleft anchor delivery shaft 808. In FIGS. 8A-8C, electrically commonelements forming electrodes are labeled “A” and “B” respectively, evenwhen physically separate.

FIG. 8A illustrates one embodiment of the present invention whereinright anchor 802, left anchor 806 and left anchor delivery shaft 808each form an electrode, the left anchor 806 and left anchor deliveryshaft 808 being electrically common elements, identified as “B”. Thisconfiguration concentrates heating or energy at the center of the rightelectrode 802 where the distance to left anchor delivery shaft 808 isless than to left anchor 806. Energy density decreases as the distancefrom the right electrode 802 increases.

FIG. 8B illustrates another embodiment of the present invention. In thisconfiguration, right anchor 802, left anchor 806 and left anchordelivery shaft 808 each form an electrode, with left anchor 806 andright anchor 802 being electrically common elements, identified as “A”.In this embodiment, medical device 800 can further include an insulator812 positioned between left anchor 806 and left anchor delivery shaft808, and a electrical connector 810 coupled to left anchor 806.Insulator 812 can be configured to provide a desired amount of RF energyinsulation between left anchor 806 and left anchor delivery shaft 808.This insulator 812 can be a dielectric coating or element, such as aceramic or polymeric hub or sleeve, or other non-conductive material toelectrically isolate left anchor 806 from delivery shaft 808. Electricalconnector 810 can be configured to enable left anchor 806 to beelectrically common with right anchor 802. Electrical connector 810 caninclude conductive metal wires, braids, conductive metallization layers,a spring or springs, flexible circuits, or other electrical connectionmeans. Copper, stainless steel, molybdenum, silver, gold, and variousconductive metal alloys may be used for the wires and/or metalizations.Furthermore, electrical connector 801 can be any means of making thedesired electrical connection between left anchor 806 and right anchor802. This connection path may occur near the distal end of the medicaldevice 800B, the proximal control handles (not shown), or anywhere inbetween.

In this configuration, when medical device 800 is positioned in the PFO,energy can be concentrated at both ends of the tunnel and can decreasetoward the center of the tunnel. For example, energy can be concentratedat concentration points 814 on left anchor delivery shaft 808 and candecrease towards a center portion 816 on left anchor delivery shaft 808.

FIG. 8C illustrates another embodiment of the present invention whereinright anchor 802 and left anchor 806 each form an electrode. In theillustrated embodiment, medical device 800 can include insulation 812positioned on left anchor delivery shaft 808. This configuration can bedesirable because it can tend to produce uniform heating along thelength of the tunnel without a very short energy flow path to theportion of the left anchor delivery shaft 808 next to the anchors 802,806.

Reference has been made herein to spaced apart structures that functionas electrodes. For instance, in FIGS. 8A-8C electrode 806 is spacedapart from electrode 802. It can be understood, however, that in otherconfigurations the electrode can be formed from one or more pairs ofalternating electrodes or conductive portions disposed relative to eachother in a desirable pattern on one or more anchors and/or deliveryshafts. For instance, an anchor or delivery shaft, catheter or tube canbe formed into an electrode by the inclusion of conductive portions.Such patterns can be formed along an axis, in concentric rings,interleaved fingers, parallel lines or curves, or in other desiredspatial relationships or configurations. The electrodes or conductiveportions can be arranged to create pairs of relatively short, lowerimpedance paths between electrodes or conductive portions where theenergy flow is be concentrated.

The shape or length of each pair, the number of pairs, the spacingbetween pairs, and their spatial relationship can be varied, resultingin energy density distributions tailored and configured as desired. Thesize and configuration of these electrodes or conductive portions can beapplied to all configurations of electrodes or anchors disclosed herein,not just to axially arranged ones. Furthermore, electrodes or conductiveportions can be configured to operate as unipolar or bipolar electrodes.Such paired electrode sets can be configured to be coupled to or form apart of the elements of the medical device, such as atrial anchors, forexample, whose purpose is to clamp the PFO closed while energy isdelivered. In a different example, a clip or implantable closure devicecan be utilized to clamp the PFO closed, the clip or implantable closuredevice can be moved through a tortuous path and can have electrode pairsdistributed thereupon.

FIGS. 9A-9D illustrate general embodiments of an element 900 having afirst electrode 902 and a second electrode 904 associated therewith inaccordance with the above. It will be understood that element 900 can bean anchor, a delivery shaft, an arm of an anchor, or any other structureof the medical devices disclosed herein or in the disclosuresincorporated herein by reference. FIG. 9A illustrate one embodiment ofthe present invention in which first and second electrodes 902, 904 wraparound a central axis in a spiral fashion along the length of the axis.Electrodes 902, 904 can be made from Kapton film with conductors on itssurface or interior. Such conductors might also be arrayed withtemperature sensors made in the same way (on the same or separate film)so that temperature sensors could be arrayed along the electrode for usein sensing tissue temperature.

FIG. 9B is a cross-sectional view of an alternative embodiment of thepresent invention in which a substantially axial electrode 900 b can beformed by placing alternating conductive and insulating tubes along anelement 900 b. For example, first electrode 902 b and second electrode904 b can be wrapped around element 900 b and separated by an insulator906 b. First and second electrodes 902 b, 904 b can be wrappedcompletely around element 900 b, can be partially wrapped around element900 b, or some combination thereof. In a simple axial electrode, pairsof conductors can be alternated at various lengths, spacing, and numberto achieve desired energy delivery. A set of such axial electrodesproperly arranged, may be joined with one or more other electrodes todistribute energy in a PFO tunnel. In this manner, electrode pairs candeliver energy doses more evenly spread along the length of a PFO. Forexample, one or more such substantially axial electrode sets could beinserted through a PFO to deliver energy inside the PFO tunnel. Theelectrode pairs can also be deployed external to the tunnel to heatother surfaces. The electrode pairs can also be used to penetrate intotissue and heat along their length while disposed inside the tissue. Forexample, a pair of axial or curved electrodes can be coupled withspreading rods, discussed with reference to FIGS. 13A-13B, to close andheat a PFO.

A set of two or more such substantially axial electrodes can be splayedthrough a PFO tunnel to distribute energy laterally in the tunnel, whileelectrode pairs which extend along the length of the tunnel can serve todistribute energy through the length of the tunnel. Alternatively,non-axial shapes and patterns of electrode pairs can be deployed, suchas loops, or other shapes can be used.

FIG. 9C is a cross-sectional view of an alternative embodiment of the anelectrode 900 c of present invention in which a first electrode 902 cand second electrode 904 c are separated one from another and positionedalong the length and on opposite sides of an insulator 906 c. In thisembodiment, electrodes 902 c, 904 c can be substantially flat. In thismanner, electrodes 902 c, 904 c can deliver energy in substantiallyopposite directions into tissues on opposite sides of the interior ofthe PFO. This energy can travel through tissues adjacent to the PFO, andtravel around the device due to insulator 906 c through a longer path tothe other electrode. This may encourage heating of surrounding tissuesdue to the fact that the shortest available path is relativelycircuitous. Optionally, one or more insulators can be positioned alongthe length of element 900 c separating first electrode 902 c from secondelectrode 904 c.

FIG. 9D illustrates an element 900 d, such as an electrode, anchor, armor delivery shaft, surrounded by a second electrode 902 d wrapped aroundelement 900 d. When element 900 d is an electrode, element 900 d andsecond electrode 902 d can be operated in bi-polar mode or unipolarmode. Element 900 d and second electrode 900 d can be electricallycommon elements and function together in unipolar mode with a ground, orcan be electrically uncommon electrodes functioning in bipolar mode, orsome combination thereof. Element 900 d and second electrode 902 d canbe configured to concentrate energy in the interior or towards thecenter of element 900 d. When element 900 d is positioned in the PFOtunnel, the heating can be concentrated in the area immediatelysurrounding the tunnel area.

The illustrated electrodes of FIG. 9A-9D are generally axiallyconfigured. In the case of electrodes with radial projecting arms, whicharm can engage or otherwise contact the surfaces of the septum, theconcentration of energy can be highest near the center of the electrodeand can decrease radially from the electrode's central axis. This can bedue to the greater spread of the arms covering a larger volume of tissuebetween electrodes per unit tissue contact length. Thus, the currentdensity can decline with distance from the central axis of theelectrodes. In the case of plate-like electrodes with substantiallyuniform contact over a larger total area of the electrode, the energydelivered can be more uniform between the electrode plates and decreaseradially from their outside diameter. Either of these approaches can beadvantageous depending on factors such as PFO anatomy, algorithms usedto deliver energy, means used to measure temperature, etc.

In some applications, because of the shape of the PFO and thepositioning of the right and left electrodes against the atrial walls,the electrodes may focus applied energy differently into the primum andsecundum. Accordingly, it can be advantageous to have electrodeconfigurations that deliver energy differently to the anatomy ofinterest. In this manner, electrode configurations can enable adaptationof the treatment of individual PFO's to their individualcharacteristics.

FIGS. 10A-10B illustrate embodiments of the present invention that canaccommodate delivery of energy differently based upon the anatomy ofinterest. In FIG. 10A, a first electrode 1000 a is illustrated having aplurality of arms or lobes 1002 a, each arm or lobe 1002 a including acontact portion 1004 a having a surface area greater than the remainderof the arm or lobe 1002 a. This contact portion 1004 a can direct RFenergy preferentially to the tissue contacting the contact portion 1004a and the tissue surrounding the contact portion 1004 a. This providesenhanced control to RF energy delivery than is currently possible. Thefirst electrode 1000 a can be used in any of the configurations ofclosure device described herein, whether left or right anchor orelectrode. As such, the discussion of first electrode 1000 a is alsoapplicable to other electrodes described herein, and vice versa.

In the illustrated embodiment, and with reference to FIGS. 10A and 1A, athree lobe 1002 a design for a right anchor 1000 a is illustrated, whichcan provide an advantageous distribution of electrical energy used toheat and close a PFO, such as PFO 50. For example, if two of the arms orlobes 1002 a are positioned on the septum primum 52 (farther from thePFO tunnel 58), and the third arm 1002 a is positioned on the septumsecundum 54 (closer to the PFO tunnel 58), the two lobes on lowersurface can inject more energy at a farther distance from the PFO 50,thus providing more heating of the tissue surrounding the PFO 50.Similarly, a three lobed left anchor can provide similar benefits. Thethree lobe design illustrated in FIG. 10A can also match the geometry ofthe entrance to the PFO 50, and thus can be advantageous in aidingrepeatable positioning. One way to modify energy delivery to the tissueis by electrically connecting one or more lobes so as to serve aselectrodes, while leaving other lobes electrically insulated. In thismanner, RF energy can be delivered to the tissue by one or more of theclamping lobes, while the electrically insulated lobe(s) serve toposition the device or to approximate tissue without RF energy delivery.

In FIG. 10B, and with reference to FIGS. 10B and 1A, a second electrode1000 b is illustrated having a plurality of arms or lobes 1002 b. In theillustrated embodiment, second electrode 1000 b includes four lobes 1002b. The four lobe design can deliver energy more evenly to both theseptum primum 52 and septum secundum 54. In this manner, tissueimmediately over the tunnel 58 may be heated relatively more than thetissues of the septum primum 54, which are farther away from the tunnel58.

In summary, the lobed electrodes 1000 a and 1000 b can be configured tosubstantially conform to the anatomy of the wall of the right atrium 30(FIG. 1B). Two of the lobes or arms of the anchor can tuck under theoverhanging portion or arch formed by the inferior aspect 55 (FIG. 1C)of the septum secundum 54, while the third lobe can span up over theseptum secundum 54. The third lobe or arm can provide clamping force andelectrical contact in a desirable location to weld the PFO closed.

Turning to FIGS. 11A and 11B, illustrated are another electrodeconfiguration and heating method. In this configuration, closure of thePFO 50 can be achieved through use of an elastomeric or polymericballoon that is filled with saline or other fluid and then heated toinitiate tissue damage and hence closure of the PFO 50 following removalof the balloon. With reference firstly to FIG. 11A, the balloon catheter1100 a includes an inflation catheter 1102 a having a lumen 1104 a toreceive a guidewire 1120 a and an inflation lumen 1106 a in fluidcommunication with a balloon 1108 a. Balloon catheter 1100 a can bemanufactured in a configuration that, when “inflated” with the fluid,assumes a desired shape in relation to the anatomy of the PFO 50, suchas illustrated in FIG. 1B. Balloon catheter 1100 a can be configured tobe compliant and substantially conform to the anatomy of the septum,PFO, etc. Once balloon catheter 1100 a is in position as illustrated,the liquid can be heated by means of a heater at or inside the ballooncatheter 1100 a. The fluid can be heated using electrical resistance, RFenergy, optical energy, or other means, whether such heat is directed tothe fluid source at the proximal end of balloon catheter 1100 a or atthe fluid within the balloon 1108 a through heating of a heating element1110 a within the balloon 1108 a as current is delivered to the heatingelement 1110 a. Another means would be to introduce electrical energythrough electrodes on the balloon's surface. Another would be to conductelectrical energy through the saline (or other conductive fluid) itself.Thus, the resistance of this conductive fluid would cause self-heatingin response to the energy flow. In any of these heating methods, thetemperature can be controlled as desired.

Balloon 1108 a, and so balloon catheter 1100 a, can be configured as asingle device or double device, as illustrated in FIG. 11B as ballooncatheter 1100 b, on one or both ends of a PFO. It could also be smallenough to reside inside the PFO tunnel when heated so as to directlyheat the interior of the PFO tunnel.

The wall thickness of balloon 1108 a or 1108 b can be varied in desiredlocations to change the heating parameters of tissue adjacent balloon1108 a or 1108 b. For example, the wall thickness of a portion ofballoon 1108 a or 1108 b can be relatively thin so as to maximize heattransfer to the tissue adjacent the reduced wall portion. In other areaswhere balloon 1108 a or 1108 b is, for example, in contact with blood inthe atrium, balloon 1108 a or 1108 b can have a thicker wall so as toreduce heat transfer to the blood or other tissues where heating is notdesired.

Turning now to FIG. 12, illustrated is another configuration of anelectrode usable to close a PFO, whether through application of RFenergy, physical anchoring and closure of the PFO, or a combination ofphysical anchoring, whether permanently or temporarily, and applicationof RF energy. As illustrated, the closure device 1200 can include adelivery sheath 1202 with an anchor 1204 disposed within a lumen 1206thereof. The anchor 1204 has a generally helical or corkscrewconfiguration where rotational movement of the anchor 1204 followingdeployment from within lumen 1206 facilitates engagement of tissuewithin and/or surrounding the PFO 50. The anchor 1204 can (i) functionto reduce the size of the PFO 50, (ii) work as an electrode, and/or(iii) simply as a means of approximating tissues so another electricalor non-electrical means or device may be used to accomplish long-termclosure.

Optionally, the anchor 1204 can include a central stem or portion 1208,illustrated in dotted lines, which can serve as a means to guide thepath of the helical or corkscrew portion of anchor 1204 as it is turnedinto the tissue of the PFO 50. Optionally, the central stem can form asecond electrode so that the anchor 1204 can operate in bipolar mode todeliver RF energy to the PFO 50. With this configuration, the heatassociated with RF energy delivery will be concentrated in the areaimmediately surrounding the tunnel 58 (FIG. 1A) when the anchor 1204 isdisposed within the PFO 50. Alternatively, the central stem 1208 and thehelical or corkscrew portion of the anchor 1204 can individually operatein unipolar mode, with a separate grounding pad or return electrode (notshown) associated with patient.

The anchor 1204 can also be used to close a PFO (or other anatomicalfeature) when used as an implantable device that would remain in thepatient after installed. The anchor 1204 can be made of material thatwould persist in the patient, or from biodegradable materials that coulddisappear after the PFO had grown closed. It can also be made of amaterial that would be implanted for a time, and then removed.

The anchor 1204 or other corkscrew or helical device could be made byseveral means. Some examples are to put a spiral slit in the end of atube, or to wind a wire (NiTiNol, stainless steel, titanium, plastic, orother material could be used) into the desired shape. In the case ofNiTiNol wire it could be formed into the desired shape and “heat set”into that shape. It could then be delivered through a small diametertube or catheter, deployed in the atrium to its helical shape, and then“screwed” into the PFO for use. For retrieval, it could be “unscrewed”from the PFO and than pulled back into its delivery tube for removalfrom the patient.

As mentioned above, the particular configuration of the anchor 1204 canaid with drawing the septum secundum 54 (FIG. 1A) and septum primum 52together. For instance, the anchor 1204 can be compliant and include anumber of turns, with the first turn having a larger diameter, or beinglarger than thy following turns. In this embodiment, the distal tip ofthe anchor 1204 can be configured to penetrate and capture tissue, forexample, at a certain diameter, such as in a PFO tunnel 58 (FIG. 1A).When the following smaller turns, or alternatively, closer spaced turns,are advanced into the tissue, the compliant nature of the anchor 1204can allow the succeeding turns to expand to follow the path created bythe first larger turn. Due to the configuration of the anchor 1204, thesmaller succeeding turns can attempt to spring back to their smallerdiameter, or in the alternative embodiment, to the closer spacing. Thisspringing back can force the tissue surrounding the PFO 50 (FIG. 1A)together, thus closing the PFO tunnel 58 (FIG. 1A). Any desired meanscan then be brought to bear to “weld” the PFO closed, such asapplication of RF energy through the anchor 1204 and/or the central stem1028. The anchor 1204 can then be unscrewed from the PFO with minimaldisruption. Alternatively, the anchor 1204 can be biodegradable, whetheror not capable of delivering RF energy to the PFO or the tunnel. In sucha case, the anchor 1204 can remain within the patient until the PFO hasclosed.

The above-described anchor 1204 provides one structure that can be usedto pull tissue together. In addition to “screwing” the anchor 1204 intothe PFO tunnel 58 as described above, pulling or pushing the ends of theanchor 1204 through use of an actuating shaft mounted to either aproximal or distal end of the anchor 1204, similar to actuating shaft118 (FIG. 2A) can aid to reduce the size of and close the PFO 50 (FIG.1A). For instance, once in place, the ends of the anchor 1204 can beeither pushed or pulled. Pushing the ends together can compress theanchor 1204 thereby capturing the tissue. Constant tissue volume cancause the tissue to squeeze into the middle, thus closing the PFO.Pulling the ends of the anchor 1204 can lengthen the anchor 1204 therebyreducing the diameter of anchor 1204. A reduced diameter can squeezetissue towards the open PFO tunnel, thus closing it.

The pushing or pulling of the anchor 1204 can be achieved, as suggestedabove, by way of an actuating shaft similar to actuating shaft 118 (FIG.2A). Alternatively, the anchor 1204 can be formed from a shape memorymaterial, such as NiTiNol or shape memory plastics, to move the anchor1204 from an open installation position to a closed, PFO closing,position. Optionally, the heat generated to activate the shape memorybehavior of a material can also heat the surrounding tissues of the PFO,i.e., application of RF energy to the anchor 1204. Alternatively, thetissue may be heated by other means, and that heat can serve to activatethe shape memory behavior. On completion of the heating step, the anchor1204 cools and becomes pliant and can be removed.

The material forming the anchor 1204, or other medical device that canbenefit from the functionality described herein, may be heated by anymeans that will change the temperature of the material to theappropriate level including: (i) passing electrical current through aconductive shape memory material, (ii) passing temperature-controlledfluid through tubes of shape memory material, (iii) optical, ultrasonic,electromagnetic, RF, or other energy means, or (iv) directed microwaves.Microwaves could also be used to heat PFO tissues themselves, combinedwith, or instead of, heating a PFO closure or heating device.

In addition to the anchor configuration described above, alternativeconfigurations of medical devices or anchors/electrodes can be utilizedto close a PFO by pushing and/or pulling. For example, intertwined oroverlapping helices or corkscrews devices similar to anchor 1204 can beutilized. These can be installed around the PFO tunnel, similar to asdescribed above with regards to the corkscrew configuration. Pullingapart causes the approximately tubular shape to decrease in diameter andgrip the PFO more tightly. Pushing can also have a beneficialcompressive effect. In a different configuration, straight elements canbe utilized, which elements can penetrate the tissue surrounding thePFO. The ends of the elements are then captured and pulled together,thus pulling the PFO together. In yet another configuration, twoelements configured with substantially straight portions and curvedportions can be utilized. The elements can be inserted into the tissuesurrounding the PFO and then come together at each end. The elements canbe configured such that as the ends of the elements are pulled together,the center sections of elements are forced together.

As with the anchor 1204, closing the above-described devices can beachieved through physically pulling or pushing ends apart or together orthrough using of the superelastic and/or shape memory characteristics ofthe material forming the device.

Turning to FIGS. 13A-13B, illustrated is another device capable of beingused to close a PFO. The anatomy of a PFO is such that its tunnel 58(FIG. 1A) is somewhat of a flattened opening formed between two tissueflaps, i.e., the septum primum 52 (FIG. 1A) and septum secundum 54 (FIG.1A). A PFO closure device 1300 may be formed from two substantiallyparallel rods that may be placed through the tunnel 58, as illustratedin FIGS. 13A-13B. In FIG. 13A, the medical device 1300 is illustrated ashaving two rods 1302 a,b positioned in the tunnel 58 of the PFO 50. Ifthese rods 1302 a,b are spread apart in the plane of the tunnel 58, asillustrated in FIG. 13B, they will stretch the edges of the tunnel 58apart, thus bringing the two more planar tunnel surfaces together. Therods 1302 a,b can be straight or curved to maintain an approximatelyeven spreading force along the length of the PFO tunnel 58. The rods1302 a,b can be configured to include curved sections or other shapescan be used to concentrate spreading forces in desired locations of thePFO 50.

Rods 1302 a,b can be formed from tubular structures, solid structures,combinations thereof, or other structures that can be used to move one alateral direction to move portions of the tunnel 58 towards each other.In this embodiment, the closure effect could be enhanced by providingports through which a vacuum may be pulled. This vacuum would tend topull the surfaces of the PFO even closure together. Additionally, onerod could deliver heated fluid such as saline, while the other rod canprovide a vacuum at its ports. If the pressure delivery and vacuum werebalanced the vacuum would still predominate so that it could continue topull the PFO closed while keeping the heated fluid localized to theinterior of the PFO. The heated fluid can heat the tissues of the PFOtunnel. Alternatively, the rods 1302 a,b can include electrodes in an RFenergy delivery system. In this embodiment, rods 1302 a,b can be used toheat the interior of the tunnel. In this manner, the energy delivery canbe distributed evenly along the length of the tunnel, and nearest theinterior surfaces of the tunnel.

Returning to FIG. 2A, as mentioned above, the left atrial anchor orelectrode 114 can be formed with the delivery shaft 110. This can beachieved using a slit-tube configuration as disclosed in U.S. patentapplication Ser. No. 11/671,428, filed Feb. 5, 2007. With theconfiguration, the arms 116 can be used to close the PFO 50. The arms116 can be configured to be either in a normally-closed ornormally-extended configuration. In a normally-closed configuration, theactuating shaft 118 is moved proximally to “pull” the arms 116 into thedesired configuration. Releasing the actuating shaft 118 returns theanchor/electrode to the low-profile configuration. In contrast, for anormally extended configuration, the actuating shaft 118 is moveddistally to move the arms 116 into the low-profile configuration used toinitially position and remove the anchor/electrode. In the former, theanchor/electrode can be removed even if the actuating shaft 118 shouldfail or become disconnected.

Another embodiment of a medical device which is configured to be used inconnection with physically closing a PFO includes electrodes or clampswith hinges or pivots. Another desirable feature of electrodes caninclude a feature that enables the electrode/clamp to pivot. Pivotingenables the electrode or clamp to become planar on the septum while acenter stem passes through a PFO that is sharply angled to the septum.Various configurations can accomplish this hinging effect. For example,in one embodiment hinged clamps can be used. The electrode or clampdevice can move into contact with the PFO, the primum, and the secundum,in such a way as to not distort the tissues inappropriately.

An electrode or clamping device can be formed which incorporates the useof hinges or pivots in place of flexures. One way to form such a pivotis to connect two relatively rigid elements with a flexible element. Oneway to accomplish this is to place a flexible element, such as, but notlimited to, a string-like thread or wire through the bore of sections oftube. It may then be knotted or attached so as to prevent the flexibleelement from being pulled out of the tube(s) when tension is applied tothe flexible element. Alternatively, such a flexible element may be usedto tie the ends of two rigid elements together. This flexible elementmay be formed from wire (e.g. nitinol, stranded wire, etc.), or fromitems such as fishing line, dental floss, thread or string as one mightfind commercially. This flexible element can be made from polymers suchas nylon, linearized polyethylene, Spectra, aramid, polyamide, Kevlar,Nomex, or other materials.

At the joint between tube segments, the segments can be free to movewith little restriction if the flexible element is left loose. Thiscreates a true hinge or pivot. The segments can be partially constrainedby applying some tension to the flexible element. This can cause the twoadjacent ends of the tube to remain next to each other, thus providingsome constraint while still allowing for relative pivoting. Pivoting canbe enhanced by providing spherical ends on one or both adjacent bead ortube ends. Examples of various hinging embodiments are set forth inFIGS. 14A-14F.

FIG. 14A discloses a medical device 1400A that can include a flexibleelement 1402, such as a securing wire and a plurality of round members1404 linked together by flexible element 1402. Round members 1404 caninclude a channel through which flexible element 1402 can be received tolink round members 1404 together. In this manner, flexible element 1402can move within round members 1404. As flexible element 1402 istightened and round members 1404 are forced together, the configurationof round members 1404 will enable round members 1404 to effectivelyfunction as a hinge.

Likewise, FIG. 14B discloses a medical device 1400B that can include aflexible element 1402 and a plurality of elements 1406 linked togetherby flexible element 1402. Elements 1406 can include an aperture throughwhich flexible element 1402 can be received to link elements 1406together. In this manner, flexible element 1402 can move through andwith respect to elements 1406. As flexible element 1402 is tightened andelements 1406 are forced together, elements 1406 can move relative toeach other and are otherwise hingedly linked together.

FIG. 14C discloses a medical device 1400C that can include a flexibleelement 1402 and a plurality of elements 1406 linked together byindividual flexible element 1402. Elements 1406 can include an aperturethrough which flexible element 1402 can be received to link elements1406 together. In this manner, flexible element 1402 can function as ahinge as elements 1406 can move relative to each other.

FIG. 14D discloses a medical device 1400D that can include a flexibleelement 1402 and a plurality of tubular elements 1408 linked together byflexible element 1402. Tubular elements 1408 can be configured such thatflexible element 1402 can be received therethrough to link tubularelements 1408 together. Medical device 1400D can include a stop 1410coupled to flexible element 1402 to facilitate forcing tubular elements1408 together as tension is applied to flexible element 1402. In thismanner, flexible element 1402 can move through and with respect totubular elements 1408, but can be prevented from pulling through tubularelements 1408 due to stop 1410. As flexible element 1402 is tightenedand tubular elements 1408 are forced together, as illustrated in FIG.14E, tubular elements 1408 can move relative to each other and areotherwise hingedly linked together at adjacent ends.

To enable a smoother hinging interaction between tubular elements 1408,alternative tubular elements 1412 a, b can be utilized, as illustratedin FIG. 14F with regards to medical device 1400F. In this embodiment,tubular elements 1412 a,b can include ends having corresponding shapes.Corresponding shapes of adjacent ends of tubular elements 1412 a,b canincrease the hinging flexibility of tubular elements 1412 a,b whenflexible element 1402 is pulled taut, as illustrated in FIG. 14F.Similarly, the substantially round members 1404 of FIG. 14A can also beprovided with corresponding shapes on their contacting surfaces toenable a smooth interaction between members 1404.

FIGS. 15A-15C illustrate an embodiment of a medical device 1500 havingself-erecting/self-configuring shaped segments 1504 that may bedelivered through a tube 1502. Segments 1504 can be sized and configuredto form a desired shape when a flexible element 1506, such as a securingwire, which is strung through segments 1504, is tensioned. For example,segments 1504 can include angled, straight or rounded edges, or caninclude a combination of shapes in order to form a desired shape whenflexible element 1506 is tensioned. Various features of segments 1504can optionally be included that maintain the rotational orientation ofone shape segment 1504 relative to another (e.g. particular end shapes,mechanical keys, a second string through a second lumen, etc.).

After segments 1504 are pushed out of tube 1502, as illustrated in FIG.15B, flexible element 1506 can be pulled. Pulling flexible element 1506can cause stop 1508 to contact and engage the adjacent segment 1504,thereby resulting in the other segments 1504 to come together to form orassume the desired shape, as illustrated in FIG. 15C. By formingsegments 1504 with angles and various shapes, as well as in variouspatterns, orientations, and sequences, specific two and threedimensional shapes can be formed when flexible element 1506 is pulled.Such a self-erecting string of beads, tubes or segments could be fedthrough a tube. When the beads, tubes or segments are out of the tube,the flexible element could be pulled, and the beads/segments preventedfrom re-entering the tube by a “pusher.” This would cause the structureto self-erect.

Various electrodes and clamps can benefit from utilizing theconfigurations of those devices illustrated in FIGS. 14A-15C, suchdevices including one or more hinges or joints as described herein. Theelectrodes disclosed herein and the references incorporated by referencecan benefit from the use of a pivot. It can be desirable to control thefree ends of a free end electrode by some means to prevent anatomicaltangling. This means can constrain the wires or arms in a way thatallows the arms to be retracted into a delivery tube after use. Onemeans of accomplishing this is to constrain these free ends byconnecting them with a pivot that will prevent the wires or arms frommoving through undesired motions, yet allow the wires or arms to movethrough desirable ones. One example of this is illustrated in FIG. 16.FIG. 16 illustrates a medical device 1600 that can include an electrodeor left atrial anchor 1602 having arms 1604 hingedly coupled to a stemor shaft 1606 by pivots or hinges 1608. As illustrated by the dottedlines in FIG. 16, as electrode/anchor 1602 is deflected, pivots orhinges 1608 enable electrode/anchor 1602 to rotate relative to stem1606.

In order to obtain the desired performance, the tips of the arms 1604 orwires can include a pivot or hinge 1608 of some kind that will partiallyconstrain the ends of the arms 1604 or wires, yet allow appropriatedeployment and shape. These hinges or pivots 1608 may be accomplished,for example, by bending the tips of the wires around each other to forma pivot, replacing the wires with tubes with an internal string, orother methods such as ball and socket or other designs.

FIG. 17 illustrates yet another medical device 1700 in accordance withan alternative embodiment of the present invention. Medical device 1700can include an anchor or electrode 1702 extending from a stem or shaft1706. Electrode 1702 can form a coil from a single (Nitinol or otherflexible) wire 1704 in which the distal end 1708 of the wire 1704 formsthe smallest coil or loop and the proximal end 1710 forms the largestcoil or loop, as illustrated in FIG. 17. Electrode 1702 can beconfigured to be received and substantially housed by shaft 1706, andcan be extended therefrom to form electrode 1702 as illustrated.

In this embodiment, when electrode 1702 is housed in tube 1706 and asthe distal end 1708 of the wire 1704 exits the delivery tube 1706, avery small coil or loop forms initially, which has little probability ofencountering anatomical structures. As more wire 1704 is deployed behindthe first coil, the electrode 1702 can assume the coiled shape in anorderly and controlled manner. A portion of the wire 1704 will rotate ina relatively smaller diameter at the center of a growing spiral. As suchit can be protected and prevented from encountering anatomicalstructures as it is deployed. The electrode 1702 can be configured toform in a plane perpendicular to its delivery tube 1706. Alternatively,the electrode 1702 can be formed to deploy such that the coil's axis isperpendicular to the axis of the delivery tube 1706. In this case, thelast wire to be pushed from the delivery tube 1706 may be configured tocause the coil to rotate over to a substantially perpendicular position.

In an alternative embodiment, the electrode can have a free end having asmall diameter coil at its distal end, which as electrode is pushed orturned out of the delivery tube, the diameter of the coils increase. Inthis embodiment, the electrode extends axially in the distal direction,such that the largest diameter coil is adjacent the distal end of thedelivery tube and the smallest diameter coil is positioned axially awayfrom the distal end of the delivery tube in the distal direction.Alternatively, the electrode can be configured to coil around thedelivery tube, such that the smallest diameter coil is positioned in theproximal direction from the distal end of the delivery tube, with thediameter of the coils increasing up to the distal end of the deliverytube.

It will be appreciated by one of ordinary skill in the art in view ofthe disclosure proved herein that electrodes of the present inventioncan be formed with a single or multiple coils. For example, a doublecoil, conical spring electrode/anchor can be formed. The first wire toexit the delivery tube forms an initial small diameter coil. The coilcan grow to a maximum and then decrease in diameter as more wire exitsthe delivery tube. It finishes with a final small diameter coil thatthen turns into a substantially straight wire that returns into thedelivery tube.

In the example of a spiral coil electrode, its stiffness and shaperecovery properties can be balanced and configured as desired by varyingthe diameter of the coils formed while varying the diameter of the wirethat forms the coil. This enables different coils having desiredstrengths to be provided. For instance, coils having thicker wire and asmaller coil, and vice versa, are possible. However, small diametercoils and thick wire both can cause undesirable strain levels in thewire when it is inside a delivery tube. This can be overcome by formingthe wire such that it has a smaller diameter in the area where thesmaller diameter coils are formed. The larger diameter coils can beformed from thicker wire because they are not required to bend astightly. The fact that stiffness of a wire increases with the cube ofthe thickness, but strain increases linearly with thickness, can be usedas an advantage in designing the coil.

An electrode formed from a shape memory material or superelasticmaterial, such as electrode 1800 illustrated in FIGS. 18A and 18B, canalso be formed such that it will deploy from a tubular shape, asillustrated in FIG. 18A, into a partly or fully unrolled shape,optionally having a flat configuration, as illustrated in FIG. 18B. Asillustrated, the electrode 1800 can include a delivery tube 1802, suchas a catheter, that defines the outer periphery of the electrode 1800while positioned in the tube 1802. The frame 1801 can support theelectrode 1800 and facilitate transition to the unrolled configuration.All or a substantial portion of the electrode 1800 can be formed of ashape memory or superelastic material.

The electrode 1800 can fit advantageously into the approximately flatPFO tunnel shape, or fit flat against anatomical structures, such as theseptum. Such flat, or partly unrolled, electrode 1800 can be deliveredthrough a delivery tube 1802 and unrolled as it exits the tube 1802. Theproximal end 1804 of the flattened shape can be configured so as tocause the proximal end 1804 to re-roll when it is retracted into thedelivery tube 1802. For instance, the proximal end 1804 can have atapered configuration such that engagement of the proximal end 1804 withthe distal end 1806 of the delivery tube 1802 induces rotational motionof the electrode 1800. This rotational motion continues as the electrode1800 is drawn into the delivery tube 1802.

According to another configuration of the present invention, anelectrode/tissue tissue clamp can be configured to contact uniformlyeven on irregular and/or non-planar surfaces. FIG. 19 illustrates aschematic representation of such an electrode, identified as electrode1900. In the illustrated embodiment, electrode 1900 can include one ormore feet 1902, 1904 configured to contact surfaces 1910, 1912,respectively. When the electrode 1900 is pushed or pulled onto asurface, such as surfaces 1910, 1912, the electrode 1900 can pivot insuch a way as to maintain contact with higher and lower areas of thesurface 1910, 1912. The electrode 1900 can include one or more hinges orjoints 1906, 1908, and 1914 to accomplish this leveling effect. In thismanner, the loads on one leg of the electrode 1900 can be approximatelyequal to the load on the other. The pivots 1906, 1908, and 1914 may beformed as true pivots, flexures, or any other hinge as discussed and/ordisclosed here.

In delivering devices to the heart or other anatomy, it can be desirableto configure the flexibility of the catheter used for delivery. Forexample, it can be desirable to achieve lateral flexibility whilepreserving axial and/or torsional stiffness. This can be accomplished byvarious tube slitting methods to achieve the desired balance ofcharacteristics. For example, a tube may be cut in various patterns toachieve a balanced combination of flexibility & stiffness. The spacing,geometry, and number of cuts, slits or holes can be varied to achieve adesired characteristic. Torsional vs. axial stiffness can be balancedand/or varied by the angles and widths of struts left between the holesor cuts, as also varying the angle of the sides of cutouts and struts.Relative position of the holes leaves wider or narrower struts indifferent directions, thus affecting flexibility and othercharacteristics.

FIGS. 20A-20C illustrate examples of cut patterns. For example, FIG. 20Aillustrates a catheter 2002 having a plurality of holes 2004 cuttherethrough. FIG. 20B illustrates a catheter 2006 having a pattern ofshapes 2008, 2010, such as diamonds, cut therethrough. As shown in theillustrated embodiment, the catheter 2006 can include uniform patterns,as with shapes 2008, can include shapes 2010 having varied position, orcan include combinations thereof. Similarly, FIG. 20C illustrates acatheter 2012 having a pattern of cut shapes along its length. In theillustrated embodiment, catheter 2012 can include herringbone patternsof slits 2018, slits around the perimeter of the catheter 2016, slitsparallel to the axis of the catheter 2014, portions of reduced wallthicknesses and/or reduced diameter, or staggered parallel slits,whether diagonal or axial. It will be understood by one of ordinaryskill in the art in view of the disclosure provided herein that theshapes and patterns can be sized, configured and positioned to provide adesired effect.

Generally, the present invention can be embodied in a number ofdifferent configurations. One skilled in the art will appreciate thatthe disclosure related to one embodiment described herein can also applyto other embodiments and structures and that the functions of one deviceor portion of the device can be used and incorporated within otherembodiments. Further, RF energy or other heating methods describedherein may be used in combination with permanently or temporarilyimplanted devices, or by bioresorbable devices to close a body lumen,such as a PFO, or “weld” tissues together.

Generally, a medical device can include a first radio frequencyconductive electrode, a second electrode spaced apart from and movablerelative to said first electrode, wherein the spacing between said firstelectrode and said second electrode is selectively changeable toaccommodate for variations in a length of a tunnel of a Patent ForamenOvale. Each of the first and second electrodes can be conductive toradio frequency energy. The medical device can further include a meansfor varying the spacing between said first electrode and said secondelectrode. The means for varying the spacing can include a deliveryshaft coupled to the first electrode. The first electrode and saidsecond electrode can be formed as separate portions of a singlecompliant electrode.

In another configuration, a medical device can include a first atrialanchor, a first delivery shaft linked to said first atrial anchor,wherein said first delivery shaft is adapted to move said first atrialanchor, a second atrial anchor, a second delivery shaft linked to saidsecond atrial anchor, wherein said second delivery shaft is adapted tomove said second atrial anchor, and a biasing member linking either (i)said first atrial anchor to said first delivery shaft or (ii) saidsecond atrial anchor to said second delivery shaft. The biasing membercan include a spring, and can link said first atrial anchor to saidfirst delivery shaft, or link said second atrial anchor to said seconddelivery shaft. The medical device can further include a second biasingmember, wherein said first biasing member links said first atrial anchorto said first delivery shaft and said second biasing member links saidsecond atrial anchor to said second delivery shaft.

In an alternative configuration, a medical device can include a firstelectrode having a stem and one or more conductive arms, wherein saidone or more arms are adapted to be coupled to said stem, a secondelectrode having one or more conductive arms, and an insulating materialcoupled to at least a portion of: (i) said first electrode, or (ii) saidsecond electrode, said insulating material adapted to reduce theconductivity of said at least a portion of said first electrode or saidsecond electrode. The insulating material can be coupled to: (i) saidfirst electrode, (ii) a portion of at least one of said one or moreconductive arms of said first electrode, (iii) a portion of said stem,(iv) a portion of at least one of said one or more conductive arms ofsaid first electrode and said stem, (v) a portion of said secondelectrode, (vi) a portion of at least one of said one or more conductivearms of said second electrode, or (vii) a portion of said first andsecond electrodes.

As described herein, a method for treating an internal tissue openingcan include placing a medical device in position to treat an internaltissue opening, said medical device comprising a first electrode and asecond electrode, wherein said first electrode and said second electrodeare adapted to operate in both a unipolar mode and a bipolar mode,positioning said first electrode adjacent a first side of the internaltissue opening, positioning said second electrode adjacent a second sideof the internal tissue opening, and operating said first and secondelectrodes between said unipolar and bipolar modes. The medical devicecan further include a conductive stem, wherein said conductive stem isadapted to operate in both a unipolar mode and a bipolar mode. Theconductive stem can be a delivery shaft or a delivery tube, as usedherein. The method can further include operating said conductive stem toheat the tissue adjacent the internal tissue opening. In this method,operating said first and second electrodes can heat the tissue adjacentthe internal tissue opening. The method can further include heating thetissue adjacent the internal tissue opening by operating said first andsecond electrodes in unipolar mode, and operating said first and secondelectrodes in bipoloar mode. The method can include first and secondelectrodes operating in unipolar mode simultaneously or at differenttime, for the same or differing durations, at the same or differingpower levels.

In another configuration, a medical device can include a first atrialanchor having one or more compliant arms, a shaft adapted to be coupledto said first atrial anchor, wherein movement of said shaft causesmovement of said first atrial anchor, a second atrial anchor having oneor more compliant arms, and a second shaft adapted to be coupled to saidsecond atrial anchor, wherein movement of said second shaft causesmovement of said second atrial anchor, wherein said second shaft isadapted to be received and movable within said first shaft. The one ormore compliant arms of said first atrial anchor can be adapted todeflect when forced against tissue, and then conform back to thepredeflected orientation when not forced against the tissue.

In still another configuration, a medical device can include a firstatrial anchor, a first delivery shaft linked to said first atrialanchor, wherein said first delivery shaft is adapted to move said firstatrial anchor, a second atrial anchor, a second delivery shaft linked tosaid second atrial anchor, wherein said second delivery shaft is adaptedto move said second atrial anchor, and a biasing member linked to atleast one of said first delivery shaft or said second delivery shaft.The biasing member can include a spring. The biasing member can linksaid first atrial anchor to said first delivery shaft. The medicaldevice can further include a handle coupled to said first deliveryshaft, wherein said biasing member links said first delivery shaft tosaid second delivery shaft, wherein said biasing member is adapted tobias the position of said first delivery shaft with respect to saidsecond delivery shaft.

In yet another configuration, a medical device can also include a firstradio frequency conductive electrode a radio frequency conductive stemadapted to be coupled to said first electrode, and a second radiofrequency conductive electrode, wherein said first electrode and saidsecond electrode are electrically common elements. The medical devicecan further include a radio frequency conductive stem, such as adelivery shaft.

In another configuration, a medical device can include a first atrialanchor, a delivery shaft adapted to be coupled to said first atrialanchor, wherein said delivery shaft is adapted to move said first atrialanchor, a second atrial anchor, a first electrode, and a secondelectrode, wherein said first and second electrodes are both coupled toat least one of said first atrial anchor, said delivery shaft or saidsecond atrial anchor. The first and second electrodes can be wrappedaround at least a portion of said at least one of said first atrialanchor, said delivery shaft or said second atrial anchor in a spiralfashion along at least a portion of the length of said at least one ofsaid first atrial anchor, said delivery shaft or said second atrialanchor. The medical device can further include an insulator coupled tosaid at least one of said first atrial anchor, said delivery shaft orsaid second atrial anchor, wherein said insulator is positioned betweensaid first electrode and said second electrode and is adapted toposition said first electrode apart from said second electrode. Aninsulator can be positioned on one or more of the first atrial anchor,second atrial anchor, or the delivery shaft. Furthermore, insulator canhave varying thickness, can have a constant thickness or can be acombination thereof, over a desired area of medical device.

Still another configuration of a medical device can include a medicaldevice having a first atrial anchor, a delivery shaft adapted to becoupled to said first atrial anchor, wherein said delivery shaft isadapted to move said first atrial anchor, a second atrial anchor, and afirst electrode, wherein at least one of said first atrial anchor, saiddelivery shaft or said second atrial anchor comprises a secondelectrode, wherein said first electrode is adapted to operate with saidsecond electrode to heat tissue adjacent said first and secondelectrodes, wherein said first electrode is wrapped around at least aportion of said at least one of said first atrial anchor, said deliveryshaft or said second atrial anchor. The first electrode can be wrappedaround said at least one of said first atrial anchor, said deliveryshaft or said second atrial anchor in a spiral fashion along at least aportion of the length of said at least one of said first atrial anchor,said delivery shaft or said second atrial anchor. The delivery shaft caninclude the second electrode, said first electrode is wrapped around atleast a portion of said delivery shaft in a spiral fashion along atleast a portion of the length of said delivery shaft.

Still another a medical device can include a first atrial anchor, adelivery shaft adapted to move said first atrial anchor, a hinge linkingsaid first atrial anchor to said delivery shaft, wherein said hinge isadapted to enable first atrial anchor to move relative to said deliveryshaft, and a second atrial anchor. The medical device can furtherinclude a second delivery shaft and a second hinge linking said secondatrial anchor to said second delivery shaft.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. Exemplary claims have been included herein toillustrate embodiments of the invention. Although exemplary claims arepresented, the invention is not limited to these claims, and theapplicant reserves the right to present different or other claims in thefuture in view of the embodiments of the invention described herein.

1. A medical device comprising: a first atrial anchor; a first deliveryshaft operatively associated with said first atrial anchor, said firstdelivery shaft being adapted to move said first atrial anchor; a secondatrial anchor; a second delivery shaft operatively associated with saidsecond atrial anchor, said second delivery shaft being adapted to movesaid second atrial anchor; and a biasing member linking either (i) saidfirst atrial anchor to said first delivery shaft or (ii) said secondatrial anchor to said second delivery shaft.
 2. The medical device ofclaim 1, wherein said biasing member comprises a spring.
 3. The medicaldevice of claim 1, wherein said biasing member links said first atrialanchor to said first delivery shaft.
 4. The medical device of claim 1,wherein said biasing member links said second atrial anchor to saidsecond delivery shaft.
 5. The medical device of claim 1, furthercomprising a second biasing member.
 6. The medical device of claim 5,wherein said first biasing member links said first atrial anchor to saidfirst delivery shaft and said second biasing member links said secondatrial anchor to said second delivery shaft.
 7. A method for treating aninternal tissue opening, the method comprising: placing a medical devicein position to treat an internal tissue opening, said medical devicecomprising a first electrode and a second electrode, said firstelectrode and said second electrode being adapted to operate in at leastone of a unipolar mode and a bipolar mode; positioning said firstelectrode adjacent a first side of the internal tissue opening;positioning said second electrode adjacent a second side of the internaltissue opening; and operating said first and second electrodes betweensaid unipolar and bipolar modes.
 8. The method of claim 7, wherein saidmedical device further comprises a conductive stem, wherein saidconductive stem is adapted to operate in the at least one said unipolarmode and said bipolar mode.
 9. The method of claim 8, further comprisingthe steps of operating said conductive stem to heat the tissue adjacentthe internal tissue opening.
 10. The method of claim 7, wherein saidoperating said first and second electrodes heats the tissue adjacent theinternal tissue opening.
 11. The method of claim 7, further comprisingheating the tissue adjacent the internal tissue opening by selectivelyoperating said first and second electrodes in unipolar mode, andsubsequently operating said first and second electrodes in bipoloarmode.
 12. The method of claim 7, wherein said first electrode and saidsecond electrode are operated in unipolar mode simultaneously.